Fixed abrasive articles

ABSTRACT

Described are fixed abrasive articles including wear indicators.

[0001] The present application is a continuation-in-part application ofU.S. patent application Ser. No. 09/563,628, filed May 2, 2000, whichclaims priority to U.S. Provisional Patent Application No. 60/132,175,filed on May 33, 1999, the disclosures of each of which are incorporatedherein by reference.

FIELD OF THE INVENTION

[0002] The invention relates to fixed abrasive articles for chemicalmechanical polishing (CMP) and has particular applicability inmanufacturing semiconductor devices.

BACKGROUND

[0003] Abrasive articles are used in a variety of industrialapplications for abrading, finishing, and polishing surfaces such asmicroelectronic devices (e.g., semiconductor devices) and magneticrecording media. Typical industrial uses of abrasive articles includepolishing a substrate, as during various phases in manufacturing.

[0004] In manufacturing semiconductor devices, a wafer typicallyundergoes numerous processing steps, including deposition, patterning,and etching. After one or more of these processing steps it is necessaryto achieve a high level of surface planarity and uniformity to enableaccurate photolithographic processing. A conventional planarizationtechnique comprises polishing, as by chemical mechanical polishing,“CMP,” wherein a wafer carrier assembly is rotated in contact with apolishing pad in a CMP apparatus. The polishing pad is mounted on arotating/moving turntable or platen. The wafers are mounted on a carrieror polishing head, and a controllable force presses the wafers againstthe rotating polishing pad. Thus, the CMP apparatus effects polishing orrubbing movement between the surface of a semiconductor wafer and thepolishing pad. Optionally, a polishing slurry containing abrasiveparticles in a solution can be dispersed on the pad and wafer.

[0005] Some polishing pads used in abrasive slurry processing include agrooved porous polymeric surface, and the abrasive slurry can be chosenaccording to the particular material undergoing CMP. The abrasive slurrycan be impregnated into the pores of the polymeric surface while thegrooves convey the abrasive slurry to the wafer undergoing CMP. Apolishing pad for use in CMP slurry processing is disclosed byKrywanczyk et al. in U.S. Pat. No. 5,842,910. Typical CMP can beperformed not only on a silicon wafer itself, but on various dielectriclayers such as silicon oxide, conductive layers such as aluminum andcopper, or a layer containing both conductive and dielectric materials,as in damascene processing.

[0006] A different type of abrasive article from the above-mentionedabrasive slurrytype polishing pad is a fixed abrasive article, e.g.,fixed abrasive polishing sheet or pad. Such a fixed abrasive articletypically comprises a backing with a number of abrasive compositeelements adhered thereto. The abrasive composite elements may includeabrasive particles in a binder, e.g., a polymeric binder. During CMP,the workpiece, e.g., wafer undergoing CMP wears away the fixed abrasiveelements thereby exposing fresh abrasive particles. A chemical agent canbe provided, e.g., in the working fluid or incorporated in the fixedabrasive article, to provide chemical activity, while the mechanicalactivity is provided by the fixed abrasive elements. Thus, such fixedabrasive articles do not require the use of a slurry containing looseabrasive particles and advantageously simplify effluent treatment,reduce the cost of consumables, and reduce dishing as compared topolishing pads that require an abrasive slurry. During CMP using a fixedabrasive polishing pad, a chemical agent can be applied to the pad, theagent depending on the particular material or materials undergoing CMP.However, the chemical agent does not necessarily contain abrasiveparticles as in abrasive slurry-type CMP operations. Fixed abrasivearticles are disclosed by Rutherford et al. in U.S. Pat. No. 5,692,950,Calhoun in U.S. Pat. No. 5,820,450, Haas et al. in U.S. Pat. No.5,453,312, Hibbard et al. in U.S. Pat. No. 5,454,844, Bruxvoort et al.in U.S. Pat. No. 5,958,794, Kaisaki in WO 98/49723, and Ravipati et al.in U.S. Pat. No. 5,014,468.

[0007] During CMP, the surface of conventional polymeric polishing padsfor abrasive-slurry type CMP operations becomes glazed, thusnonreceptive to accommodating and/or dispensing the abrasive slurry, andotherwise incapable of polishing at a satisfactory rate and uniformity.Accordingly, conventional practices comprise periodically conditioningthe pad surface so that it is maintained in a proper form for CMP.Conventional conditioning means comprises a diamond or silicon carbide(SiC) conditioning disk to condition the polishing pad. After repeatedconditioning operations, the pad is eventually consumed and incapable ofpolishing at a satisfactory rate and uniformity. At this point, thepolishing pad must be replaced. During replacement, the CMP apparatus isunavailable for polishing with an attendant significant decrease inproduction throughput.

[0008] There exists a need to extend the useful life of a fixed abrasivearticle while simultaneously maintaining high wafer-to-wafer ratestability. There also exists a need for a CMP apparatus enabling the useof fixed abrasive polishing pads having an extended life and achievinghigh wafer-to-wafer rate stability. There also exists a need for fixedabrasive articles, methods of manufacturing fixed abrasive articles, CMPapparatus employing fixed abrasive articles and CMP methods using fixedabrasive articles which: enable a reduction in contamination during CMP;improve CMP as by facilitating web removal; avoid formation of airbubbles under a fixed abrasive web; facilitate application of chemicalsduring CMP; allow tailoring of a fixed abrasive article for use toprocess a variety of substrate materials; reduce and/or eliminatingindexing; dissipate heat during CMP; improve conformance of thepolishing web during CMP; condition a fixed abrasive element; increasethe amount of web material stored on a roll; monitor CMP; optimize theuse of chemicals during CMP; optimize controlling CMP temperature;tailor the chemical agent during CMP; reduce particulates in the CMPeffluent; detect and analyze effluent particles to determine theircomposition; control the particles in the effluent to reduce scratchingand dishing; determine the useful lifetime of fixed abrasive elementsduring CMP; optimize the lifetime of a fixed abrasive article; optimizeindexing; and generally improve the efficiency, increasing manufacturingthroughput and reducing cost of CMP.

SUMMARY OF THE INVENTION

[0009] The present invention relates to methods and fixed abrasivearticles that incorporate a wear indicator. The methods and articlesallow a user to monitor and determine the useful lifetime and the end ofthe useful lifetime of fixed abrasive articles, and to optimize, e.g.,maximize, the actual amount of use of the fixed abrasive article.

[0010] As a fixed abrasive article works against a substrate, to abradeor polish, etc., abrasive composite elements are abraded and wear downover time. According to the invention, the abrasion of the abrasivecomposite elements causes a change of a feature or property of the fixedabrasive article or its interaction with the substrate. Monitoring thefixed abrasive article or the process to detect that change allows anobjective basis for identifying an optimal point in the lifetime of afixed abrasive article to replace that fixed abrasive article.

[0011] Normally in processing substrates with a fixed abrasive article,the fixed abrasive article must be stopped and examined to determinewhether the abrasive article should be replaced with a fresh abrasivearticle. These interruptions are inefficient and can be avoided by usingmethods and fixed abrasive articles of the invention. And while thereplacement of worn fixed abrasive articles can cause inefficiencies anddown-time, neglecting to replace a worn abrasive article presents thepossibility of damaging substrates being processed. On the other hand,to replace the abrasive article prematurely, at a time when the abrasivearticle still has significant useful life, causes inefficiencies andincreases processing costs due not only to the cost of failing to fullyuse the abrasive article, but also by unnecessarily causing additionaldown-time during excessive replacements. The present invention allowsfor optimal use of a fixed abrasive article and minimizes the number oftimes fixed abrasive articles need to be replaced during processing.

[0012] An aspect of the invention relates to a fixed abrasive articlecomprising a three-dimensional abrasive composite in the form ofabrasive composite elements, and further comprising a wear indicator.

[0013] Another aspect of the invention relates to a fixed abrasivearticle comprising posts having an inert chemical or mechanicalindication to indicate post consumption.

[0014] Throughout this application, the following definitions apply:

[0015] An “abrasive agglomerate” refers to a plurality of abrasiveparticles bonded together in the form of a unitary particulate mass.

[0016] An “abrasive composite element” refers to one of a plurality ofshaped bodies which collectively provide a textured, three-dimensionalabrasive article, e.g., comprising abrasive particles and a binder,wherein the abrasive particles may be in the form of abrasiveagglomerates.

[0017] The invention provides a relatively low cost, readilycontrollable method for improving the surface characteristics of asemiconductor wafer at various stages during fabrication. Because theabrasive article is designed to be relatively long-lasting, a singleabrasive article may be used in a number of successive operations.

[0018] Other features, advantages, and constructs of the invention willbe better understood from the following description of figures and thepreferred embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIGS. 1 through 20 relate to various fixed abrasive articles.FIGS. 2, 11, and 13-20 relate to embodiments of fixed abrasive articlesand processes that include wear indicators.

DETAILED DESCRIPTION

[0020] A fixed abrasive article is an abrasive article capable ofremoving material from a surface of a workpiece, especially in thepresence of an appropriate working fluid. Preferred fixed abrasivearticles can be of the type that include an abrasive composite. Abrasivecomposites are known in the art of fixed abrasive articles, and mayinclude polymeric materials, phase separated polymeric materials, or acombination of either or both of these with abrasive particles such asinorganic or polymeric abrasive particles. As an example, an abrasivecomposite can comprise a binder and optionally inorganic abrasiveparticles dispersed throughout the binder. As another example, anabrasive composite can comprise a polymeric material having separatephases, with one phase acting as abrasive particles.

[0021] The fixed abrasive article can be an integral abrasive articlethat is substantially free of unattached abrasive particles except asmay be generated during use. Preferably, the fixed abrasive article canbe “three-dimensional,” “textured,” “erodable,” or a combination ofthese. A “three-dimensional” fixed abrasive article is a fixed abrasivearticle having abrasive particles dispersed throughout at least aportion of its thickness such that removing some of the particles duringplanarization exposes additional abrasive particles. A “textured” fixedabrasive article is a fixed abrasive article having raised portions andrecessed portions in which at least the raised portions contain abrasiveparticles and binder. An “erodable” fixed abrasive article is a fixedabrasive article that breaks down under use conditions in a controlledmanner.

[0022] The fixed abrasive article of the invention can include anabrasive composite that is a “precisely-shaped” abrasive composite,which is an abrasive composite having a molded shape that is the inverseof a mold cavity used to make the precisely-shaped abrasive composite,and which is retained after the abrasive composite has been removed fromthe mold. Preferably, the abrasive composite of a precisely-shapedabrasive article is substantially free of abrasive particles protrudingbeyond the exposed surface of the shape before the abrasive article hasbeen used, as described in U.S. Pat. No. 5,152,917 (Pieper, et al.),incorporated herein by reference.

[0023] Fixed abrasive articles are known in the abrasive arts, and aredescribed, for example by Rutherford et al. in U.S. Pat. No. 5,692,950,Calhoun in U.S. Pat. No. 5,820,450, Haas et al. in U.S. Pat. No.5,453,312, Hibbard et al. in U.S. Pat. No. 5,454,844, Bruxvoort et al.in U.S. Pat. No. 5,958,794, Kaisaki in WO 98/49723, and Ravipati et al.in U.S. Pat. No. 5,014,468, the entire disclosures of each of which areincorporated herein by reference.

[0024] Binders for fixed abrasive articles are generally known in theart of fixed abrasive articles, and a variety of materials useful asbinders are commercially available. The binder can be a polymericmaterial capable of containing the abrasive particles for use, and canbe prepared from one or more reactive chemistries. Preferred binders canbe prepared from polymerizable resins, as are known, such as organicpolymer resins, e.g. thermoset resins. Examples of preferred resinsinclude acrylate and methacrylate polymer resins. Another type ofsuitable binder is a ceramer binder that includes colloidal metal oxideparticles in an organic polymer.

[0025] Preferably, the abrasive composite can be erodable. Erodibilityis desired because it results in abrasive particles being removed fromthe abrasive article to expose new abrasive particles. Because it can bepreferred that the abrasive article be three-dimensional, a plentifulsupply of new abrasive particles will be assured. If the abrasivecomposite is not erodable, the abrasive particles may not properly bedischarged from the abrasive article during use, in which case freshabrasive particles will not be exposed. If the abrasive coating is tooerodable, abrasive particles may be expelled too quickly, which mayresult in an abrasive article with a shorter than desired product life.

[0026] For specific applications, the degree of erodibility of anabrasive composite can be a function of a variety of factors, including:the surface textures of the fixed abrasive article and the workpiece,including the shape of the abrasive composite elements; the conditionsof use, including the pressure between the fixed abrasive article andthe workpiece and whether a liquid is used during the process; and thecomposition of the substrate.

[0027] To facilitate erodibility, the binder preferably contains aplasticizer in an amount sufficient to increase credibility of the fixedabrasive article relative to the same fixed abrasive article that doesnot contain plasticizer. Preferably, the binder includes at least about25% by weight of the plasticizer (more preferably, between about 40% andabout 75% by weight) based upon the combined weight of the plasticizerand the resin. Preferred plasticizers are phthalate esters, as well asderivatives thereof. See, e.g., U.S. Pat. No. 5,958,794.

[0028] The abrasive particles can be any size, composition, or type thatwill be useful in the abrasive article, depending on factors such as theparticular composition of the abrasive article (e.g., the binder), theworkpiece with which the abrasive article is designed to process, andwhether or not a liquid is intended to be used during processing. Ingeneral, abrasive particles having an average particle size no greaterthan about 5 micrometers are preferred. Even more preferred are abrasiveparticles of no greater than about 1 micrometer, in particular nogreater than about 0.5 micrometer.

[0029] In specific applications, e.g., to avoid harming a surface of aworkpiece such as a semiconductor wafer (particularly where the wafersurface is a metal oxide-containing surface such as a silicondioxide-containing surface), the abrasive particles may be selected tohave a Mohs hardness value no greater than about 8. Examples ofpreferred abrasive particles include particles made of metal oxidematerials such as ceria. See also Bruxvoort et al., U.S. Pat. No.5,958,794, at column 19, lines 6-40, and Kaisaki, WO 98/49723, for otherexamples of abrasive particles.

[0030] The abrasive composite may also contain other particles, e.g.,filler particles, in combination with the abrasive particles, in amountsthat are understood in the art of fixed abrasive articles. Examples offiller particles include carbonates (e.g., calcium carbonate), silicates(e.g., magnesium silicate, aluminum silicate, calcium silicate, andcombinations thereof), and combinations thereof. Plastic fillerparticles may also be used.

[0031] Abrasive composite elements can take any useful form or shape,positive or negative, with preferred shapes including cylindrical,cubical, truncated cylindrical, prismatic, conical, truncated conical,truncated pyramidal, cross, postlike with flat top surface,hemispherical, and combinations of these. Appropriate sizes and spacingsof the elements will also be appreciated and understood by a workerskilled in the art of fixed abrasive articles. Generally, useful shapesof the abrasive composite elements can be any shapes that will usefullyabrade or polish a selected workpiece, preferably in the form of athree-dimensional, erodable element. Preferably, substantially all ofthe abrasive composite elements have the same shape.

[0032] Abrasive composite elements may be directly adjacent or spacedapart from each other. For example, they may be provided in the form ofelongated ridges spaced apart from each other, e.g., such that channelsform between adjacent abrasive composite ridge elements. Each of theabrasive composite elements can preferably have substantially the sameorientation relative to the backing.

[0033] Preferred are fixed abrasive articles that include a plurality ofabrasive composite elements arranged in the form of a precisely-shapedpattern. All of the elements preferably have substantially the sameheight, which is most preferably no greater than about 250 microns.

[0034] The fixed abrasive article is preferably long lasting, e.g., ableto complete at least two, preferably at least 5, more preferably atleast 20, and most preferably at least 30 planarization processes. Theabrasive article should preferably provide a good cut rate.Additionally, the abrasive article is preferably capable of yielding aprocessed workpiece, e.g., semiconductor wafer, having an acceptableflatness, surface finish, and minimal dishing. As will be appreciated bya skilled artisan, the materials, desired texture, and process used tomake the fixed abrasive article all influence whether or not thesecriteria are met.

[0035] The fixed abrasive article may preferably contain a backing, asis known. One example of such an article is illustrated in FIG. 13. Ingeneral, abrasive particles are dispersed in a binder to form anabrasive composite bonded to the backing. Referring to FIG. 13, abrasivearticle 50 comprises backing 59 having front surface 58. Abrasivecomposite 57 is bonded on front surface 58. Fixed abrasive article 50 istextured and three-dimensional, and comprises a plurality of erodableabrasive composite elements 54. The upper surface of the fixed abrasivearticle. i.e., the side of the fixed abrasive article having a face thatincludes the abrasive composite elements 54, will be referred togenerally as the abrasive surface 52. In the figure, abrasive compositeelements 54 are pyramids. There are recesses or valleys 53 betweenadjacent abrasive composite elements. There is also more than one row ofpyramidal abrasive composite elements shown in which the second row ofabrasive composite elements is offset from the first row. Abrasivecomposite elements 54 comprise a plurality of abrasive particles 56dispersed in binder 55. Outermost point 51 of each abrasive composite 54first contacts a workpiece during processing, and as processing proceedsthe abrasive composite elements wear or erode away substantiallyuniformly toward backing 59.

[0036] Fixed abrasive article 50 of FIG. 13 includes an example of awear indicator, which is a visible marker at the base of an abrasivecomposite element 54, and which is illustrated by shaded portion 60.After an amount of abrasive composite element 54 is worn or eroded away,the visible marker becomes visible at the upper (abraded) surface offixed abrasive article 50.

[0037] Optionally, as illustrated in FIG. 14, the fixed abrasive articledoes not require a separate backing. FIG. 14 shows fixed abrasivearticle 600 which comprises a textured, three-dimensional abrasive bodyhaving a textured abrasive surface 602 making up a general abrasivesurface 606, and being provided by an integral structure composed of aplurality of pyramidal-shaped abrasive composites 604 in which abrasiveparticles 601 are dispersed in a binder 603. A visible marker isincluded as a wear indicator, as represented by shaded area 605.

[0038] Embodiments of the abrasive article can be circular in shape,e.g., in the form of an abrasive disc; an abrasive roll, typicallyreferred to in the abrasive art as an abrasive tape roll; or in the formof an endless abrasive belt.

Measuring Wear of Fixed Abrasive Articles Using Wear Indicators

[0039] The fixed abrasive articles of the invention allow formeasurement of the wear or remaining useful lifetime of a fixed abrasivearticle, e.g., to determine useful, convenient, optimal, or excessivedegree of wear of a fixed abrasive article. In preferred methods, thiscan be accomplished during processing of a workpiece, and without havingto interrupt processing to view the stationary fixed abrasive article;i,e., without interrupting processing for the purpose of displacing thefixed abrasive article from contact with the workpiece, and possiblystopping motion of the fixed abrasive article, to allow viewing of thefixed abrasive article and the amount of wear it has experienced. Thefixed abrasive articles allow a determination of whether or when a fixedabrasive article should be replaced with a fresh fixed abrasive article.Replacing the fixed abrasive article after an optimal amount of weareliminates the possibility of damaging substrates by using too much ofthe fixed abrasive article, and creates efficiency by minimizing thenumber of times that fixed abrasive articles are replaced, thereforereducing over time the total amount of process down-time required toreplace worn fixed abrasive articles.

[0040] A wear indicator is a component, feature, shape, or design of afixed abrasive article that is designed into the article to causemeasurable change in the fixed abrasive article during use, and that canbe used to measure a change during use in the fixed abrasive article orthe process, indicating that the fixed abrasive article has experiencedwear, in that the amount of useful abrasive composite that remains apart of the fixed abrasive article has been reduced. In terms ofphysical makeup or composition, the wear indicator can be a component,feature, shape, or design of a fixed abrasive article whose composition,position, or incorporation into the fixed abrasive article is differentfrom the usual composition, position, or incorporation of such acomponent, feature, shape, or design; a wear indicator would nottypically be a normal component of a fixed abrasive article such asbinder, abrasive particle, etc., but if its position, design, orincorporation in the fixed abrasive article is designed to produce adetectable change upon wear of the fixed abrasive article, such afeature of the fixed abrasive article could be considered a wearindicator.

[0041] Preferred wear indicators are added to those other normallynecessary materials and features of the fixed abrasive article, such asnecessary binder and abrasive materials. Examples of preferred wearindicators involve the use of materials that affect a visual property ofa fixed abrasive article or a process using the fixed abrasive article,such as a colorant or dye; a transparent material that is transparent tosome form of radiation or that can be measured in terms of an index ofrefraction; detectable materials such as magnetic or metallic materials;materials that are chemically detectable, either directly or indirectly,e.g., through a chemical reaction or change in pH; or, the wearindicator can be a shape or form of a fixed abrasive article such as avoid or an aperture in the fixed abrasive article that becomes visibleor otherwise detectable after a certain amount of wear occurs, or thatcan be used to monitor another process parameter or physical feature ofthe process that will change with wear of the fixed abrasive article.

[0042] The wear indicator can operate according to any chemical,physical, mechanical, electrical or other principle. Examples includethe following: the wear indicator may operate using principles ofelectricity with electrical devices such as capacitors or othercapacitive, inductive, resistive, or conductive devices (e.g., if a wearindicator is or has properties of one of these devices or can bedetected by any of these devices or related principles); principles ofoptics, by monitoring changes in color or refractive index of a fixedabrasive article, a wear indicator, or another component or aspect of aprocess that uses the fixed abrasive article, such as may evenincorporate the workpiece or a liquid used in the process; theprinciples relating to magnetism, e.g., by use of a magnetic wearindicator such as a magnetic wear bar, a magnetic film, magnetic powder,magnetic paint, or any other magnetic material; principles relating tofriction between a fixed abrasive article and a workpiece, i.e., as thefixed abrasive article experiences wear and abrasive composite erodesaway, the moving force of friction between the fixed abrasive articleand the substrate either increases or decreases resulting in an increaseor decrease in motor torque that can be easily measured (e.g., contactbetween the wear indicator and the fixed abrasive article may increaseor decrease the amount of friction between the fixed abrasive articleand the substrate); or, the wear indicator may operate by making a noiseor even further abrasion, e.g., a scratch, in the workpiece, uponcontacting the workpiece (although these alternatives may not bepreferred if they may damage the substrate). The choice of an operativeprinciple to be used and the selected components of the fixed abrasivearticle may depend on a large number of factors such as the choice ofthe workpiece, the processing equipment, the desired precision of theprocess, and dimensions of the workpiece or the fixed abrasive article.

[0043] Generally, wear indicators that relate to features that can bereadily and visually observed, e.g., using visual optics, can bepreferred. As an example, a wear indicator may operate on principles ofa change in a visual property of a fixed abrasive article that occurswith wear of the fixed abrasive article.

[0044] The change may be a gradual change that can be measured andmonitored throughout the life and use of the fixed abrasive article, orit may be an abrupt, rapid, or sudden, visual change such as a visualmarker that is uncovered after an amount of wear, or that is visibleuntil the marker is abruptly worn away from a surface of the fixedabrasive article.

[0045] More generally, exemplary wear indicators include those thatcause a feature or property of the fixed abrasive article to change asthe fixed abrasive article wears. Whether the change is gradual orabrupt, the wear indicator preferably causes a feature or property ofthe fixed abrasive article to change in a predictable, detectable andmeasureable fashion wherein that change can be correlated to a degree ofwear of the fixed abrasive article. This type of a wear indicator canoperate by becoming detectable or undetectable, or by becomingrelatively more or less detectable, as the fixed abrasive article wears,especially as abrasive composite elements of the fixed abrasive articleare worn or eroded away whereupon the fixed abrasive article experiencesor causes a detectable change based on the presence of the wearindicator. Such a wear indicator can be a properly placed visual markersuch as a visible pigment, colorant, dye, or the like, incorporated intothe fixed abrasive article in a manner that will cause the visualcharacter of the fixed abrasive article to predictably change with useand wear of the fixed abrasive article, especially when the fixedabrasive article wears down to allow contact between the wear indicatorand the workpiece.

[0046] As one specific example, a fixed abrasive article can include avisual wear indicator in the form of a colored layer over abrasivecomposite elements, e.g., over at least a portion of the abrasivesurface, or over the entire abrasive surface. Fixed abrasive article 620illustrated in FIG. 15 includes a colored layer 622, e.g., a paint,applied over pyramidal abrasive composite elements. The abrasivecomposite elements can be of any shape, as long as the amount of wearindicator remaining on the fixed abrasive article will change (e.g., bereduced) with use and wear of the fixed abrasive article, and the changecan be measured. Preferred shapes can include at least one non-verticalwear surface, such as pyramids or ridges, as shown in FIG. 15, that willexperience a color change when the abrasive surface is viewed. Otherexamples include hemispherical elements, conical elements, and evencylindrical elements, especially those that include a shoulder, ledge,ring, or other form of a nonvertical surface, e.g., step or a ramp, thatif coated with a colored layer will gradually or abruptly change colorduring use of the fixed abrasive article.

[0047] An example of another type of wear indicator is a visual markersuch as a visible pigment, colorant, or dye, etc., that becomes visibleafter an amount of fixed abrasive article is used and worn away Thevisual marker may be incorporated into the fixed abrasive article in anymanner that will cause the visible wear indicator to become visible withuse and wear of the fixed abrasive article.

[0048] Specific examples of this type of wear indicator include wearindicators that are present at a position that causes the wear indicatorto become visible or otherwise detectable (or relatively more or lessvisible or detectable) after some of the abrasive composite element isworn or eroded away. FIG. 2 illustrates exemplary abrasive article 2comprising abrasive composite elements 4 in the form of posts. Theabrasive composite elements 4 include a binder and abrasive particles(the abrasive particles are not specifically shown) and a visiblemarker, e.g., a visible dye, at a lower portion 10 of the elements 4.During use, portions 6 of the elements that do not contain visible wearindicator, i.e., the portions above the portions 10 that do containvisible wear indicator, will wear or erode away. Upon such erosion downto the level of the abrasive composite element where the visual wearindicator is first present, represented by lines 8 in FIG. 2, the wearindicator becomes visible. The abrasive article can then be replacedwith a fresh abrasive article. Visual wear indicator may be present inone, several, or all of the abrasive composite elements of such a fixedabrasive article, e.g., in a pattern such as a circle or line, or withinall abrasive composite elements of a fixed abrasive article.

[0049] The wear indicator of FIG. 2 need not be visual, but can be anymaterial that becomes detectable upon contact with the workpiece, afterwear of the abrasive composite elements. As another example, lowerportion 10 may include a chemical, e.g., dispersed or encapsulated, thatwill evolve from the fixed abrasive article when lower portion 10contacts the workpiece during processing. The chemical may be directlydetectable in the atmosphere of the process or may be indirectlydetectable in the effluent or working fluid of the process, for exampleby reacting with another material to cause a color change, a pH change,or some other detectable chemical phenomena.

[0050] The height of the portions 10 of the abrasive composite elements4 that contain wear indicator can be selected as desired to cause thewear indicator to be detected at a desired time during the life of thearticle, after a desired amount of wear. This depends to a great extenton the height of the abrasive composite element itself and on the shapeof the abrasive composite element. In a general sense, the wearindicator can preferably be included in only the bottom 25 percent (byheight) of the abrasive composite element, e.g., the bottom 5 or 10percent by height. Also, the portions 10 of the abrasive compositearticle may or may not, as desired, include abrasive particles. Suchconsiderations will be readily understood by one of skill in the artrelating to fixed abrasive articles.

[0051] Another example of a wear indicator is depicted at FIG. 11. Inthis embodiment a wear indicator element 12 (represented by the shadedarea), i.e., a “swear indicator composite,” comprising a binder and awear indicator, is located in an abrasive article 16 in a space betweenabrasive composite elements 14. The wear indicator element 12 is notnecessarily a portion of an abrasive composite element (although it maywell include a binder and abrasive or other particles), because it doesnot have to take on the shape or composition of a fixed abrasivecomposite element. Here, wear indicator element 12 can be considered aseparate component of the fixed abrasive article, shown in this exampleto be attached to abrasive composite elements 14. The upper surface ofwear indicator element 12 comes into contact with a surface of asubstrate when adjacent posts 14 have worn down to the level of thesurface of wear indicator element 12. Wear indicator element 12 thenprovides some indication that the wear indicator element 12 iscontacting the substrate. This indication can be, e.g., by a visualindication, for example a color change, e.g., a color may appear ordisappear upon abrasion of the surface of the wear indicator element 12;by a magnetic indication, e.g., by sensing a magnetic wear indicatorcoated on the top surface of wear indicator element that upon contactwith the substrate will abrade away; by an increase in friction orabrasion caused by the contact; by the presence of another type ofmaterial eroded out of the wear indicator element 12 such as a chemicalthat is directly or indirectly detectable in the effluent, workingfluid, or atmosphere of the process; or by any other effectivemechanism. Wear indicators of this type may be placed at one or atnumerous different positions throughout an abrasive surface of a fixedabrasive article, e.g., between abrasive composite elements. There maybe one or a number of such wear indicators over a surface of a fixedabrasive article, and a group of wear indicators may optionally form apattern such as a line or circle that will be visible during use, e.g.,while the abrasive article is spinning or otherwise moving.

[0052] In FIG. 11, the wear indicator element 12 of abrasive article 16can be comprised of any of the previously-identified materials usefulfor wear indicators, including a binder, and including any one or moreof a visual marker, a metallic material, a magnetic material, etc., oran abrasive material such as abrasive particles. As one embodiment, anupper surface of wear indicator 12 can be coated with a colored coating(not shown) that wears away when posts 14 wear down to the level of theupper surface; at that level of wear, the colored coating wears away andcauses a change in the fixed abrasive article color that indicates thata degree of wear has occurred.

[0053] As yet another example, a wear indicator can be embedded in aknown position in a fixed abrasive article, and as the fixed abrasivearticle wears the relative position of the wear indicator can bemonitored to monitor how much of an abrasive composite has worn away.Specifically, such a wear indicator can be in the form of a wear bar orstrip such as a detectable, e.g., colored, metallic, or magnetic striplocated at or below a surface of a fixed abrasive article, or placedbetween layers (e.g., a layer of abrasive composite, a sub-pad, or asubstrate or backing) of a fixed abrasive article. As the fixed abrasivearticle wears, the distance between the wear indicator and the surfaceof the workpiece will change (e.g., decrease). Such a distance can bemeasured and monitored, and when a certain distance between the wear barand the workpiece surface is reached, the fixed abrasive article can bereplaced. The distance can be measured directly or indirectly, using thewear indicator, by any suitable technique. As a single example, adistance of a magnetic material from a workpiece surface can be measuredusing a Hall Effect sensor. A signal strength, as sensed by a read head,could grow in magnitude as the distance closes.

[0054] An example of this embodiment is shown in FIG. 16. In the figure,fixed abrasive article 630 comprises an embedded wear bar 632. The wearbar can be any material that is detectable and whose position can bedetermined through the abrasive article 630. Examples of usefulmaterials for the wear bar can depend on the composition of the fixedabrasive article and the method used for detecting the position of thewear bar. Some useful materials include metallic materials, magneticmaterials, and possibly even colored materials if at least a portion ofthe fixed abrasive article is transparent to visible light. While FIG.16 shows a wear bar, the detectable material may take any useful form.In use, the fixed abrasive article contacts a substrate 640 and wearsaway abrasive composite elements 604, which reduces the distance 636between the wear bar 632 and the surface 638 of substrate 640. Thedistance 636 can be measured by measuring the position of the wear bar632, and this can be used to keep track of the amount of wear and theuseful lifetime remaining of fixed abrasive article 630; i.e., when acertain minimum distance is reached, the fixed abrasive article 630 canbe replaced with a fresh fixed abrasive article.

[0055] Yet another exemplary type of a wear indicator is an abradablewear indicator that is included in a fixed abrasive article at aposition such that the wear indicator can be detected when present butthat will wear away after a certain amount of wear of the fixed abrasivearticle, especially wear of the abrasive composite elements.

[0056] Examples of abradable wear indicators can be abradable visiblemarkers, magnetic or metallic paint or other materials, or any otherdetectable and abradable material placed at a surface of the fixedabrasive article or within a fixed abrasive article at a desired depth.

[0057]FIG. 11 can be used to illustrate an abradable wear indicator on asurface of a fixed abrasive article. As previously mentioned, the uppersurface of wear indicator element 12 can be coated with an abradablewear indicator (not shown) such as a detectable colored, metallic, ormagnetic material. During the useful lifetime of fixed abrasive article16, the abradable wear indicator is present and detectable; upon wear ofthe abrasive composite elements 14 to and past the level of the surfaceof the wear indicator element 12, the abradable wear indicator coated atthe surface of the wear indicator element 12 will abrade away and nolonger be detectable.

[0058]FIG. 18 illustrates an abradable wear indicator located below asurface of, e.g., embedded in, a fixed abrasive article 618. Abradablewear indicators 607 are located below abrasive surface 602, embedded inabrasive composite elements 604 at a depth that will cause them to bedetectable while present, but where they will be worn or abraded away asabrasive composite elements 604 wear down. The depth of abradable wearindicators 607 can be a depth below surface 602 that will cause theindicators 607 to wear away at a desired, optimal, or convenient timeduring the life of fixed abrasive article 600. Also, while FIG. 18 showsthree abradable wear indicators in the form of linear elements or bars,any number and any size or shape, may be used.

[0059] As described, wear may be measured in some embodiments of theinvention by monitoring a change observable in a characteristic of theabrasive surface of the fixed abrasive article, by observing theabrasive surface (i.e., “front-side”) of the fixed abrasive article.Other embodiments of wear indicators can be used by observing thebackside of the fixed abrasive article, especially through a window,hole, or other aperture in the fixed abrasive article and its mounting.

[0060] Some examples of wear indicators that might be monitored from thebackside of the fixed abrasive article include wear indicators that areviewable through the abrasive article, either because the abrasivearticle is transparent to a mechanism used to sense the wear indicator(e.g., “sensing radiation”), or because an aperture is included in thefixed abrasive article. The mounting must also be designed to allowmonitoring of the wear indicator from the backside.

[0061] One example of a wear indicator that can be observed from abackside of a fixed abrasive article is a wear indicator that works onthe principle of optics, wherein wear of the fixed abrasive articlecauses one or more of: a change in the optical nature of a path throughthe fixed abrasive article, or a change in the optical nature of a paththrough the fixed abrasive article and to the workpiece, possiblythrough a liquid used with the fixed abrasive article in modifying theworkpiece.

[0062] More specifically, a fixed abrasive article as illustrated inFIG. 17 can include a transparent wear indicator 646 in the form of asolid but transparent window, e.g., aperture (hole), glass,polycarbonate, or another material that is transparent to a type ofsensing radiation, and that allows a sensing radiation, e.g., in theform of a beam, to pass through the window and back. The transparentwear indicator does not have to be transparent to visible radiation, andradiation other than visible radiation can be useful.

[0063] The optical properties of the wear indicator can be monitored todetermine when the wear indicator contacts the workpiece. This can beaccomplished, for example, by measuring an optical property of the path648 starting below the fixed abrasive article 644 and moving upwardthrough the wear indicator 646, through space 642, and to surface 638 ofworkpiece 640. The optical property may be a color or an index orrefraction, or the like. During use of fixed abrasive article 644,abrasive composite elements 604 maintain a distance and a space 642between wear indicator 646 and surface 638 of workpiece 640. Space 642can be detected from the backside, i.e., underside, of fixed abrasivearticle 644 by monitoring an optical property of the wear indicator andthe space. Space 642 between wear indicator 646 and workpiece surface638 will exhibit optical properties such as color and index ofrefraction that can be detected through wear indicator 646. The opticalproperty will be affected by the optical properties of the workpiece andoptical properties of ally liquid used in processing. The liquid may bepresent in space 642, as may air, and the presence of either or bothwill affect optical properties along line 648. When abrasive compositeelements 604 wear away to a degree that wear indicator 642 contactssubstrate surface 638, the optical property being measured will changein a predictable fashion because space 642 will be eliminated and theoptical properties observed through the wear indicator along line 648will be essentially the properties of wear indicator 646 in contact withworkpiece surface 638 (perhaps through a thin layer of air or liquid).Observation of these optical properties can be correlated to the amountof wear and the remaining life of the fixed abrasive article.

[0064]FIG. 19 illustrates how a wear indicator can take the shape, form,or design of a fixed abrasive article, e.g., a form, shape, design of anabrasive composite or a wear indicator composite, and in the figure, theform of a void or apperature designed into the fixed abrasive article.Specifically, fixed abrasive article 619 includes voids 608 extendingpartially through fixed abrasive article 619, starting from the bottom.Upon wearing of the portions of abrasive composite elements 604 locatedjust above voids 608, the voids will become visible apertures throughthe fixed abrasive article. These can be detected visually or based on achange in the frictional forces between the fixed abrasive article and asubstrate, or otherwise.

[0065] As an alternative embodiment, not illustrated, a wear indicatormay take the form of an aperture through the fixed abrasive article,that is used to introduce a working fluid to the process. The aperturemay be through any portion of the fixed abrasive article, such asthrough an abrasive composite element in the form of a post, or at anarea between abrasive composite elements, e.g., defining a pore orgroove. This type of wear indicator can be used by monitoring a processparameter that relates to the aperture, that changes during wear of thefixed abrasive article. For example the pressure or leakage rate of theworking fluid flowing through the aperture will change with the gradualwearing away of the fixed abrasive article, and can be correlated(during processing) to the degree of wear of the fixed abrasive article.

[0066] As yet another possibility, a wear indicator can be of a typethat can be monitored through the workpiece, e.g., either a workpiecethat is transparent to some type of sensing radiation, or that includesholes or apertures that allow viewing of the fixed abrasive article, theworkpiece, a liquid involved in processing, or a combination of these.An example of a transparent workpiece is a glass workpiece such as atelevision faceplate polished using diamond polishing techniques. Visualwear indicators that change color gradually or abruptly, either byappearing, fading, or disappearing, can be particularly useful with atransparent substrate, but other types of wear indicators will also beuseful.

[0067] Other embodiments of wear indicators incorporated into fixedabrasive articles will be apparent from the foregoing disclosure, andmight include one or more of the above concepts and specific productembodiments, or others. For example, a wear indicator may be in the formof a marker at the base of an abrasive composite element of any of thevarious useful shapes and sizes of abrasive composite elements, or as acomponent located between abrasive composite elements of any shape.

[0068] The fixed abrasive articles can be used in modifying the surfaceof a workpiece (also sometimes referred to as a “substrate”). Somemethods of using the fixed abrasive articles are apparent from thedescription above, but also relate to the more specific examples asfollows.

[0069] The workpiece may be any workpiece that can be processed, e.g.,abraded, polished, or otherwise modified, using a fixed abrasivearticle. Preferred processes involve the modification of a surface of asemiconductor, especially but not necessarily by incorporating methodsof chemical mechanical polishing.

[0070] A semiconductor substrate can comprise a microelectronic devicesuch as a semiconductor wafer. A semiconductor wafer may comprise eithera substantially pure surface or a surface processed with a coating oranother material. Specifically, a semiconductor wafer may be in the formof a blank wafer (i.e., a wafer prior to processing for the purpose ofadding topographical features such as metallized and insulating areas)or a processed wafer (i.e., a wafer after it has been subjected to oneor more processing steps to add topographical features to the wafersurface). The term “processed wafer” includes, but it is not limited to,“blanket” wafers in which the entire exposed surface of the wafer ismade of the same material (e.g., silicon dioxide). One area in which themethod can be useful is where the exposed surface of a semiconductorwafer includes one or more metal oxide-containing areas, e.g., silicondioxide-containing areas

[0071] It is generally desired to modify a workpiece surface to achievea surface that is more “planar” and/or more “uniform” and/or less“rough” than the workpiece surface prior to treatment. The particulardegree of “planarity,” “roughness,” and/or “uniformity” desired willvary depending on the individual workpiece and the application for whichthe workpiece is intended, as well as the nature of any subsequentprocessing steps to which the workpiece may be subjected. In general,however, there are several known methods of measuring “planarity,”“roughness,” and/or “uniformity.”

[0072] Methods of modifying a workpiece surface using a fixed abrasivearticle are well known, and generally include contacting a workpiece anda fixed abrasive article with a desired pressure and relative motion,e.g., rotational, linear, or otherwise, between them.

[0073] Certain methods, e.g., planarization processes, can be conductedusing a liquid in contact with the workpiece and the fixed abrasivearticle, with the liquid being chosen based on the composition of theworkpiece, to provide the desired planarization without adverselyaffecting or damaging the workpiece.

[0074] The liquid may contribute to processing, in combination with thefixed abrasive article, through a chemical mechanical polishing process.As an example, the chemical polishing of SiO₂ occurs when a basiccompound in the liquid reacts with the SiO₂ to form a surface layer ofsilicon hydroxides. The mechanical process occurs when an abrasivearticle removes the metal hydroxide from the surface.

[0075] The pH of the liquid may affect performance of the abrasivearticle in modifying a workpiece, and can be selected as desired, basedon the nature of the workpiece surface being planarized, including thechemical composition and topography. Where the workpiece comprises asilicon wafer surface that also contains a metal oxide (e.g., silicondioxide), the liquid may be an aqueous medium having a pH greater than5, preferably greater than 6, more preferably greater than 10. A pH inthe range from 10.5 and 14.0 can be preferred, e.g., from about 10.5 to12.5. Examples of suitable chemistries for use with a copper workpieceare described in Kaisaki WO 98/49723, and in Assignee's copending U.S.patent application Ser. No. 09/266,208, filed Mar. 10, 1999, andincorporated herein by reference.

[0076] Examples of liquid media suitable for use in modifying metaloxide-containing wafer surfaces include aqueous solutions containinghydroxide compounds such as potassium hydroxide, sodium hydroxide,ammonium hydroxide, lithium hydroxide, magnesium hydroxide, calciumhydroxide, barium hydroxide, and basic compositions containing compoundssuch as amines and the like. A basic liquid medium may also contain morethan one basic material, e.g., a mixture of potassium hydroxide andlithium hydroxide. An example of a metal hydroxide-containing liquidmedium is a solution of potassium hydroxide in deionized or distilledwater in which the potassium hydroxide concentration ranges from about0.1 to 0.5% (e.g., about 0.25%).

[0077] The liquid may also include a chemical etchant, especially inmodifying a surface of a semiconductor wafer. Although not wishing to bebound by theory, it is theorized that a chemical etchant may “attack”and possibly react with an outermost surface of a semiconductor wafer.The abrasive article then removes the resulting material formed on theoutermost surface of the semiconductor wafer. Examples of chemicaletchants include strong acids (e.g., sulfuric acid, hydrofluoric acid,and the like) and oxidizing agents (e.g., peroxides).

[0078] The liquid may also, if desired, help break down the surface of afixed abrasive article, thereby increasing the erodibility and the rateof erosion of the fixed abrasive article during use. For example, wherethe fixed abrasive article includes an abrasive composite containing awater-soluble binder or a watersensitive filler such as wood pulp, awater-containing liquid medium will result in water dissolving or beingabsorbed into the abrasive coating, thereby enhancing erodibility of thefixed abrasive article.

[0079] The liquid may also contain additives such as surfactants,wetting agents, buffers, rust inhibitors, lubricants, soaps, and thelike. These additives are chosen to provide desired benefits whileavoiding damaging a workpiece surface. A lubricant, for example, may beincluded to reduce friction between the fixed abrasive article and asemiconductor wafer surface during planarization.

[0080] Inorganic particulates may also be included in the liquid. Theseinorganic particulates may aid in the cut rate. Examples of suchinorganic particulates include: silica, zirconia, calcium carbonate,chromia, ceria, cerium salts (e.g., cerium nitrate), garnet, silicatesand titanium dioxide. The average particle size of these inorganicparticulates should be less than about 1,000 Angstroms, preferably lessthan about 500 Angstroms and more preferably less than about 250Angstroms.

[0081] The amount of the liquid is preferably sufficient to be usefulwith a particular substrate, e.g., to aid in removal of metal hydroxidedeposits from a surface of a semiconductor wafer.

[0082] After processing of a workpiece is complete, the workpiece can beprocessed as desired, e.g., a semiconductor wafer is typically cleanedusing procedures known in the art.

[0083] During use in modifying a surface of a workpiece, the fixedabrasive article can preferably be secured to a sub-pad. The sub-padallows for processing of the workpiece, including contacting the fixedabrasive article to the workpiece, wherein the contact pressure betweenthe workpiece surface and the fixed abrasive article (i.e., the totalwafer backside pressure) depends at least in part on the particularabrasive article. In general, the contact pressure preferably does notexceed about 10 psi.

[0084] According to the invention, processes using the fixed abrasivearticle to modify a surface of a workpiece can make use of the wearindicator to monitor the use, remaining life of, or the need to replacethe fixed abrasive article. The fixed abrasive article, can be monitoredin any fashion to detect a change indicating that a threshold amount ofwear has occurred on the fixed abrasive article. Examples of changesinclude changes in the form or a property of the wear indicator, such asits visibility or detectability by other visual, optical, or non-visualproperties. Specifically, the wear indicator may become detectable,e.g., visible, especially after abrasive composite elements are worndown to an extent that the wear indicator contacts the substrate, ornearly so; simple contact between the wear indicator and the workpiece,as measured by a noise, added friction, scratching or abrasion of thesurface of the workpiece, or a visual indication; a change in form or aproperty of the fixed abrasive article, e.g., its color or averagecolor; a change in the distance or spacing between the workpiece and thewear indicator, for the substrate being less than a minimum distancefrom the wear indicator, as measuring the position of the wearindicator; etc.

[0085] As a specific example, a wear indicator can be a visual markersuch as a dye, and the process using the fixed abrasive article caninclude visually monitoring the abrasive surface of the fixed abrasivearticle. This can be done either by displacing the abrasive article fromcontact with the workpiece, or, preferably, by setting up a mechanismfor visually monitoring the abrasive article during use and while thearticle remains in contact with and continues to process the workpiece.Preferably, continuous monitoring of the abrasive article during use canbe accomplished, for example, using a fixed abrasive article in the formof a belt, wherein the belt moves around rollers and a surface of thebelt contacts the workpiece, optionally with motion of the workpiece.Such processing methods are well known and understood in the art ofprocessing using fixed abrasive articles. Because the entire surface ofthe abrasive article belt does not contact the workpiece during use, thebelt can be monitored visually and when a visual wear indicator becomesvisible, the belt can be changed. Visual monitoring can be done by aworker or may be done electronically.

[0086]FIG. 20 illustrates a simplified apparatus for planarizingsemiconductor wafers using fixed abrasive articles of the invention.Apparatuses of the type illustrated and numerous variations and othertypes of apparatus are well known for use with polishing pads and looseabrasive slurries. An example of a suitable commercially availableapparatus is a CMP machine available from IPEC/WESTECH of Phoenix, Ariz.

[0087] As shown in FIG. 20, apparatus 30 comprises head unit 31 that isconnected to a motor (not shown). Chuck 32 extends from head unit 31; anexample of such a chuck is a gimbal chuck. Chuck 32 preferably isdesigned to accommodate different forces and pivot so that the fixedabrasive article can maintain desired surface finish and flatness on thewafer.

[0088] At the end of chuck 31 is wafer holder 33 to help securesemiconductor wafer 34 to head unit 31 and prevent the semiconductorwafer from becoming dislodged during planarization.

[0089] The speed at which wafer holder 33 rotates will depend on theparticular apparatus, planarization conditions, abrasive article, andthe desired planarization criteria. In general, however, wafer holder 33rotates between about 2 to about 1,000 rpm, typically between about 5 toabout 500 rpm, preferably between about 10 to about 300 rpm and morepreferably between about 30 to about 150 rpm. If the wafer holderrotates too slowly or too fast, then the desired cut rate may not beachieved.

[0090] Wafer holder 33 may rotate in a circular fashion. Optionally, aswafer holder 33 rotates, the wafer holder may oscillate or vibrate e.g.,in a circular spiral, figure eight, corkscrew, or other uniform,nonuniform, or random fashion. Preferably, the size of fixed abrasivearticle 39 is larger than the size of wafer holder 33, and furthermore,the process includes motion between the fixed abrasive article 39 andthe wafer holder 33 such that the wafer holder 33 moves relative to thefixed abrasive article 39 and contacts different areas of the fixedabrasive article surface 42. The relative sizes of fixed abrasivearticle 39 and wafer holder 33 can be sufficient that a portion of thesurface area of the fixed abrasive article does not contact theworkpiece, and therefore remains visible. The visible area can bemonitored.

[0091] The fixed abrasive article will typically have a diameter betweenabout 10 to 200 cm, preferably between about 20 to 150 cm, morepreferably between about 25 to 100 cm. The abrasive article may rotatebetween about 5 to 10,000 rpm, typically between about 10 to 1000 rpmand preferably between about 10 to 250 rpm. It is preferred that boththe semiconductor wafer and the fixed abrasive article rotate in thesame direction. However, the semiconductor wafer and the fixed abrasivearticle may also rotate in opposite directions.

[0092] Apparatus 30 also has base unit 41 which holds fixed abrasivearticle 39 having abrasive surface 42. Sub-pad 40 is connected to baseunit 41 and is attached to fixed abrasive article 39. In general, thesub-pad should be resilient such that during planarization the fixedabrasive article will planarize the entire semiconductor wafer surface.It is preferred that sub-pad be made from a conformable material such asa polyurethane foam.

[0093] A preferred embodiment of the process can be as follows. Athreedimensional, textured fixed abrasive article is provided thatcomprises a plurality of abrasive composite elements bonded to abacking, the abrasive composite elements comprising a plurality ofabrasive particles and a binder. A wear indicator is included in any ofthe various forms such as a visual marker, e.g., a dye present at a baseof one or more abrasive composite elements, and in an amount andposition that will become visible after a pre-determined amount of theabrasive composite elements are worn or eroded away during use.

[0094] A sub-pad is attached to and generally coextensive with thebacking of the fixed abrasive article. The sub-pad comprises: at leastone resilient element having a Young's Modulus of less than about 100MPa and a remaining stress in compression of at least about 60%; and atleast one rigid element generally coextensive with and interposedbetween the resilient element and the backing of the fixed abrasivearticle, wherein the rigid element has a Young's Modulus that is greaterthan that of the resilient element and is at least about 100 MPa.Suitable sub-pad constructions are disclosed in U.S. Pat. No. 5,962,950.

[0095] The abrasive article can be in the form of a disc having adiameter that is appropriate for the workpiece, e.g., typically greaterthan 25 cm, often greater than 36 cm and sometimes greater than 50 cm indiameter.

[0096] Referring to FIG. 20, reservoir 37 holds liquid 43 which ispumped through tubing 38 into the interface between semiconductor wafer34 and abrasive surface 42.

[0097] During planarization there can optionally be a consistent flow ofthe medium to the interface between the abrasive article and thesemiconductor wafer.

[0098]FIG. 20 also illustrates how wear of a fixed abrasive article canbe monitored according to the invention, using a visual wear indicator.FIG. 20 illustrates a photodetector 49 that monitors the color of fixedabrasive article 39. During processing, abrasive composite elements offixed abrasive article 39 wear down or erode, exposing a visual (e.g.,colored) marker that can be detected by photodetector 49. When thevisual marker is detected, fixed abrasive article 39 is understood to beworn and can be replaced with a fresh fixed abrasive article.

Production of Fixed Abrasive Article Comprising a Wear Indicator

[0099] Fixed abrasive articles of the invention can be prepared by knowntechniques of preparing fixed abrasive articles, and one of ordinaryskill in the arts of abrasives and fixed abrasive articles willunderstand how a wear indicator can be incorporated into a fixedabrasive article.

[0100] A generally-stated method of providing a three-dimensional,textured, fixed abrasive article is as follows. A slurry containing amixture of a binder precursor and abrasive particles is applied to aproduction tool having cavities which are the negative of the desiredshape of a textured surface of a fixed abrasive article. A backing isbrought into contact with the exposed surface of the production toolsuch that the slurry wets the surface of the backing. Then the bindercan be at least partially solidified, cured, or gelled. The fixedabrasive article can be removed from the production tool and fully curedif it was not fully cured in the previous step. Alternatively, theslurry can be applied to the surface of the backing and then theproduction tool can be brought into contact with the slurry on thebacking. The abrasive composite thereby takes the form of a plurality ofabrasive composite elements adhered to the backing.

[0101] A wear indicator can be incorporated into the fixed abrasivearticle using techniques that will be apparent to those skilled in theart of manufacturing fixed abrasive articles. These can includeincorporating the wear indicator into an uncured binder precursor usedin preparing the fixed abrasive article, e.g., incorporating the wearindicator into some or all abrasive composite elements of a fixedabrasive article, as desired, preferably at a consistent depth.

[0102] A wear indicator taking the form of a detectable material coatedover a portion or the entirety of an abrasive surface of a fixedabrasive article can be prepared by simply applying such a coating to atleast a portion of the fixed abrasive article.

[0103] Other methods can be used to produce a fixed abrasive articlewherein a wear indictor is incorporated into, e.g., embedded into,abrasive composite elements or wear indicator composite elements, oreven a backing or any other component of the fixed abrasive article.

[0104] Generally, a wear indicator can be provided in a backing orbetween a backing and abrasive composite elements of a fixed abrasivearticle, or any other layer, by lamination or coating techniques.

[0105] As another example, cavities of a production tool may bepartially filled with a slurry that contains binder precursor andabrasive particles, and the slurry may optionally be partially or fullycured. A wear indicator may be applied to the open surface of theslurry. For example, a layer of a visual indicator, e.g., a paint or adye, may be coated over the open surface, and the remaining cavity spacecan be filled. Alternatively, after partially filling the cavities, aprecursor (a “wear indicator precursor”) comprising a binder precursorand a wear indicator such as a dye or pigment, could be used topartially or fully fill the remaining space of one or more of the toolcavities. The wear indicator precursor contains a binder precursor oranother curable or hardenable material, which may then be fully orpartially cured, and the cavities, if not already full, may be filled tocompletion. For convenience, efficiency, or cost, wear indicatorprecursor need not include abrasive particles. More generally, the spaceor spaces of the cavities filled after the wear indicator precursor hasbeen added need not contain abrasive particles, because the wearindicating portion of the abrasive article need not function as anabrasive, although it of course may, if abrasive particles are includedtherein.

[0106] Another method of providing a three-dimensional, textured, fixedabrasive article with a wear indicator is generally as follows. Abacking having a contour generally corresponding to the desired shape ofthe textured surface is provided. A slurry of abrasive particles in abinder precursor is then coated onto the contoured surface of thebacking and cured in such a manner that the cured abrasive compositewill have a textured surface corresponding generally to the contour ofthe backing. A wear indicator may be incorporated into the fixedabrasive article produced by this method, e.g., by locating a marker ator below a surface of the backing, at a depth and position that willcause the marker to become detectable after an amount of wear occurs onthe abrasive composite elements. Alternatively, the marker can beincorporated into the slurry in positions that will cause the marker todetectably change or to become detectable after an amount of wear occurson the abrasive composite elements. A visual marker disposed throughoutthe slurry will produce a product analogous to that of FIG. 15 that willchange in color as the abrasive composite element formed from the slurrywears away and exposes the backing (of a different color).

[0107] Certain additional modifications may be made in the a fixedabrasive article to improve or otherwise alter performance. For example,the abrasive article may be perforated to provide openings through theabrasive layer and/or the backing to permit the passage of fluidsbefore, during or after use.

EXAMPLES

[0108] The inventions disclosed and claimed herein address and solveproblems found in the abrasives product and processing arts, improveefficiency, and reducing costs of CMP processing, while maintainingwafer-to-wafer uniformity and the quality of semiconductor devices. Theinventions set forth herein are illustrated by the embodiments set forthhereinafter, which are not to be construed as limiting the invention.

Embodiment No. 1

[0109] The inventive concept resides in providing a permeable web tointroduce chemicals, e.g., a microporous web. Advantages further includepreventing air bubbles under the web. The web material itself ispermeable to the supply chemicals

[0110] A problem which arises during CMP is effective supplyingchemicals underneath the wafer resulting in starvation at the wafercenter. This would apply to both fixed abrasive and conventional slurryCMP. As the wafer rotates, a leading edge-trailing edge situationarises. But in any case, around the edge of the wafer at some point allof the different points on the edge get to be leading at some point andall of them get to be trailing at some point, but the center is alwaysthe center. Adverting to FIG. 1, the leading and trailing edges andchemical concentrations are shown. There may be some depletion acrossthe wafer during rotation and the wafer is rotating around the center ofthe wafer. Thus, the center of the wafer always experiences some mediumchemical concentration. Accordingly, the chemical concentration is goingup and down and up and down causing a very unstable situation. Thisproblem is solved by providing a permeable abrasive pad so that thewafer sees a uniform concentration of chemicals everywhere. The web ispermeable in a vertical direction, coming up from the bottom. Thechemicals would be supplied through the platen itself up directlythrough the membrane.

[0111] Another advantage is that if air bubbles are trapped, byproviding a non-flat surface to the abrasive, it would permeate out. Thebottom is shown in FIG. 1.

[0112] This arrangement is not incompatible with vacuum hold down,because by sucking it through a semipermeable membrane a pressure dropacross the membrane occurs and this is what provides the necessary holddown.

[0113] Aspects include patterns of vacuum channels on one part andchemical supply channels on another part. The vacuum hold down is,therefore, dispersed evenly enough to get a good hold down on a filmwithout localized tearing. The chemistry supply would go up through thefilm with proper spacing of the air and chemical supply channels.

Embodiment No. 2

[0114] This invention entails impregnating the plastic matrix of a webwith process chemicals. FIG. 2, depicts a post of abrasive material.Such posts are typically about 50 microns tall and about 200 microns indiameter. But the shape of it in no way limits the invention. Duringpolishing, the first wafer is at the top of the post, which wears downso that later wafers are exposed to a lower part of the post.

[0115] There are a number of different functions performed by the CMPchemistry, e.g., oxidizers, inhibitors, such as corrosion inhibitors,buffers, and chelating agents. Ergo, there are a number of differentroles performed that vary somewhat, depending on the particular system,e.g., copper, tungsten or oxide. However, the concept of chemicalimpregnation would be the same.

[0116] For illustrative purposes, in a Cu system, the oxidizers attackthe copper and oxidize it to get copper oxide. That performs twofunctions. Initially, a corrosion barrier is provided where there is noabrasion—it is self limiting where rubbing does not occur. Therefore,etching stops. But in the high spots, the oxide is more prone to polishthan the copper metal. Therefore, the oxide is polished and thenreoxidized, polished, and then reoxided. The oxide is not a good enoughbarrier in the low spots, and that is why some corrosion inhibitors,e.g., BTA, are included to basically assist the oxidizer in capping thesurface in the low spots where not undergoing polishing. The mechanicalaction of polishing on the high spots removes both the oxide layer andthe inhibitor so that it initiates a fresh attack of the copper.Chemical buffers are employed to maintain the pH in the solution becausethese chemicals are pH active—it is an electrochemical type of a processwhich is dependent on pH. Chelating agents take the copper in thesolution and maintain it in solution so that the material rubbed off isremoved instead of redepositing on the wafer.

[0117] It is particularly advantageous to impregnate a buffer into theplastic matrix to maintain a desired pH. The buffer impregnated in theplastic matrix is continually supplied at the exact point needed—rightat the point of polishing. Thus, any of the types of chemicals could besupplied into the posts, e.g., buffers, oxidizers, inhibitors, etc.

[0118] There are several advantages of putting the chemicals into theposts. One is that it provides a timed release. As the post wears down,more and more chemical is provided in a very controlled manner.

[0119] The pad refers to the squishy stuff supplied as a backing eitherintegral or nonintegral with the web material itself, which is thebacking film that carries the posts and posts themselves. From a veryminimalistic standpoint, the web is the posts and the backing. For theweb, as in going reel to reel, it is just the backing and the posts, andthe squishy sub-pads are supplied independently. It is the poststhemselves that are in contact with the wafer. Thus, as the posts weardown fresh chemicals are continually exposed for timed release, therebyobtaining a more constant concentration over time right at the point ofcontact where it is desired.

[0120] Moreover, web manufacturers can determine how much chemicals toinclude, which is more controllable than depending on a technician torefurbish chemicals, since it is always going to be the sameconcentration depending on your manufacturability position, rather thanwhat is going on in the field or if the equipment is breaking down.

[0121] Another aspect comprises introducing a chemical marker down nearthe bottom of the posts that is inert to the process but detectable,thereby providing a signal when approaching the end of the posts. Suchchemicals can include an organic dye, that would not adversely interactwith the process chemistry. When it starts getting released it would bevery obvious to the eye because of a color change. In addition, opticaldetectors can be installed in the effluent stream. Another aspect ofthis embodiment comprises detecting a drift in process uniformity fromfirst wafer to a subsequent wafer, and correcting the drift by suitablechemistry in the posts.

Embodiment No. 3

[0122] This embodiment involves forming a fixed abrasive web with aplurality of posts having different shapes, different sizes, differentheights, different materials and having different distributions ofparticles. This provides the ability to tailor a web for differentfunctions, for example, simultaneous CMP of metal and oxide.

[0123] This embodiment solves the problem of process drift over time bytailoring a number of posts in contact over time so that when some ofthem wear down, the wafer starts engaging more and more posts. Anotherproblem stems from a rate difference between initial contact of theposts and subsequent post contact after some CMP. The first contact withlower posts would experience a different rate.

[0124]FIG. 3, shows examples of two different shapes. By combining thedifferent shapes on the web the benefits of the different shapes areachieved. Later on in the process, copper, for example, begins to clearover oxide and a barrier layer of Tantalum (Ta) is exposed. The Ta mustalso be removed stopping on the oxide. This aspect involves tailoringthe selectivity, whereas, conventionally, the web is very selective toboth Ta and oxide, e.g., about 500 to 1 on Ta and about 250 to 1 onoxide.

[0125] Aspects of this embodiment include a web with a selectivity of 1to 1 to 1, as by strategically formulating the posts with suitablechemistry for targeted etching.

[0126] Varying the shape, height and diameter of the posts to obtaindifferent structures or patterns can be easily implemented. Smallerposts have a better removal rate and faster abrasion, because thesmaller ones have the ability to dig better.

Embodiment No. 4

[0127] This invention includes the concept of varying thecompressibility of the web to obtain non-linear compressibility toeffectively treat both high and low spots on a wafer. Under compression,the modulus of compressibility would increase significantly as thematerial is compressed to about 50%, as with common sealant elastomersthat are loaded with a silica filler to provide strength and body. Asthe squishy sealant is compressed, the polymer compresses, but uponfiller to filler contact, compression ceases completely, i.e., a verynon-linear compressibility. In this embodiment, a post is provided sothat when a force is applied, it can compress a certain amount, but thenfurther force doesn't compress it any further, i.e., a nonlinear spring.As illustrated in FIG. 4, with a wafer having a high part and a lowpart, the high part contacts the post and compress it to obtain a largeforce. Where they are in contact with the low parts, a weak force isobtained. By providing a non-linear force, part of the wafer protrudes anumber of microns beyond a low spot and compresses a post to a greaterextent making it even stiffer so that it pushes back harder. The modulusof compressibility of the post can be changed by suitable crosslinkingin the polymer, varying the amount of filler, or changing the nature ofthe polymer, e.g., a more linear polymer or a more trifinctional or evena quadrifunctional polymer. This is well known art in the polymerindustry.

[0128] The inventive concept is that, as the wafer is pressed down, inthe limit, only the high points on the wafer will automatically contactthe pad for polishing. Each post will vary in its modulus ofcompressibility depending on the amount of force applied to it. Thus,each post is similar to a little spring and the frictional force varieswith the applied force. In a linear spring, the force is relativelyconstant with displacement. However, with non-linear springs, as in thisembodiment, if sufficient pressure is applied, the force dramaticallyincreases, thereby automatically applying greater force to the highspots on a wafer vis-a-vis low spots.

Embodiment No. 5

[0129] Advantageously, a fixed abrasive polishing web comprising a heatdissipating material can overcome the problems associated with excessheat build-up during polishing. In an aspect of this embodiment, theheat dissipating substance is incorporated into the posts and/orassociated backing sheet. Thermally conductive materials include a metalpowder, e.g., iron, nickel, copper, zinc, tin, lead, silver, gold,titanium, tungsten, palladium, bismuth, indium, gallium, aluminum andalloys thereof, metallized polymers or metallized ceramics such asalumina, silica, glass, polyamide, polystyrene, polyetheramide,polyacetylene, polyphenylene, polyphenylene sulfide, polypyrol,polythiophene, and graphite. The conductive elements may be provided inmany forms, such as for example, particles, wires, filaments, andmetallized flakes. The elements may have a wide variety of regular andirregular shapes, as for example, spheres, rods, flakes, and filaments.The binder can be a thermoplastic or a thermosetting-type polymer or amonomer which will polymerize to form the thermally conducted substratehaving the thermally conducted elements therein.

Embodiment No. 6

[0130] This embodiment relates to a fixed abrasive web comprising aplurality of elongated posts on a sheet. Conventional posts have adiameter of about 125 to 1,000 microns, with the diameter about twicethe height. Accordingly, conventional posts extend up to 500 micronsabove the backing sheet. The present embodiment comprises forming postswith a ratio of the height to diameter opposite conventional practices,so that the posts are significantly higher than their diameter. In thisway, a multiplicity of very tall posts are formed, as shown in FIG. 5.Instead of polishing on their upper edges, these tall posts lean overlike bristles and polish on their sides that wear off during CMP. Thus,the tall posts are formed so that they lean over during CMP and flowbrushing from the side and round off at the top.

[0131] Advantageously, according to this embodiment, only a small amountof force is required to bend over the individual posts. However, theforce would increase as the taller posts bend to contact each other anyare stacked upon each other side by side. At this point, the down forcegets compressed. Aspects of this embodiment include forming posts havinga height of about one micron to about ten microns and spaced apart aboutone micron to about ten microns.

Embodiment No. 7

[0132] This embodiment comprises preconditioning fixed abrasive articlescomprising a plurality of posts so that the posts have equal heightsabove the backing to achieve a uniform texture, i.e., uniform abrasivesurface on the posts. In this way, each post has exactly the same topsurface, i.e. uniform surfaces and uniform heights. This objective canbe implemented by physical dressing, as by an abrasive material which isharder than the abrasive material of the posts, pre-seeding with aslurry including polishing debris. By pre-seeding employing polishingdebris, the first wafer effect is eliminated. The first wafer effect isconventionally encountered and involves initial non-uniformity with theinitial wafer. It is believed that subsequent wafers are polished in thepresence of polishing debris. Accordingly, by pre-seeding with polishingdebris, the first wafer effect is eliminated.

[0133] Another aspect of the present invention comprises the use of alaser to precondition the posts. See FIG. 6.

Embodiment No. 8

[0134] This invention relates to improvements with respect to in siturate measurement (ISRM) devices. The ISRM device is a laser base devicethat shines a light though the web material to provide a measurement offilm thickness. The web material is a composite of abrasive filler and apolymer binder. The dispersed particles typically have a differentrefractive index than the matrix thereby resulting in scattering. It istherefore, very difficult to get the laser through with detectableintensity, particularly since it has to make the trip twice, (i.e.) ithas to go in reflect and come back out. This embodiment solves thatproblem changing the refractory index of the polymer matrix to matchthat of the abrasive particles. The refractory of the polymers caneasily be adjusted to match it to about that of the refractory index toobtain totally clear material. See FIG. 7.

[0135] Embodiments of the present invention include abrasive particlesand binders made of a laser light transparent material. For example,both abrasive particles and the binder can be made of a transparentpolymer, e.g., a polyurethane, a polycarbonate, an epoxy resin;inorganic minerals, e.g., sapphire, glass, quartz; or hard organic orsemi-organic materials, e.g., diamond or germanium.

Embodiment No. 9

[0136] The invention resides in forming a fixed abrasive web withnegative posts, as in U.S. Pat. No. 5,014,468 and incorporatingchemicals in the negative recesses. Typically, the posts form about10-25 percent of the surface of the pad, leaving at least about 75% asopen channel, i.e., a connected phase employing terminology frompercolation theory. The connected phase is the one connected all the waythrough. The open space is the connected phase; the posts aredisconnected from one another. This embodiment reverses the conventionalfixed abrasive pad by making the open space the disconnected phase andmaking the posts the connected phase, thereby maintaining the samerelative amount of post area. However, a region can be walled off ordamned, as by forming a hexagonal recess which is isolated, such thatthe posts constitute walls around these isolated recesses. In theprocess of contacting the web and the wafer, the chemicals are suppliedin these recesses. The chemicals are primarily liquid and the concernwith the posts where the open spaces, the connected phases, is that theliquid can mix around and go around. If the chemicals are supplied inthese isolated recesses, then the chemicals are going to be transportedwith the web and remain in one place. Therefore, the chemistry isbasically isolated through a number of different little cells, each cella pocket. A circuitous or tortuous path can be formed between the postsso that you're not totally isolated, but effectively isolated. See FIG.8.

Embodiment No. 10

[0137] This embodiment resides in proving a non-homogenous web withdifferent areas to perform different functions, thereby providinggreater flexibility. For example, posts can be used to perform buffing.This embodiment provides macroscopic regions of the web which aredifferent for different functions. For example, one area of the web canbe for copper polish and another area for example, would remove Ta,thereby achieving a macroscopic effect. This can be easily implementedin round/round polishing when the wafer travels around in a circle onthe web material, and it rotates in its place. See FIG. 9.

[0138] The wafer effectively describes a circle around on the webmaterial and, therefore, the track of the center is at a uniformdistance in a circular path around on the web. However, the edgessometimes extend further out and sometimes further in, because they arealso rotating as the wafer goes around. Accordingly, polishing isenhanced, as, for example, at the center, versus the edge, byintroducing a strip of material where the center would spend more timeover that strip. The concept includes altering the behavioralperformance of the web in different regions, in macroscopic regions, toalter performance of for example, under the edge on the wafer.

Embodiment No. 11

[0139] The problem addressed by the present invention is that theconventional web backing material, i.e., believed to be apolyester-based material, sheds on abrasion. Frictional interactionbetween the platen and the web during advancement generates particles inthe process. The solution to this problem resides providing anonshedding backing material, such as a self-lubricating plastic. Suchself-lubricating plastics are conventional. See FIG. 10.

[0140] Examples of self-lubricating polymers include fluorinated alkane,e.g., Teflon, fluorinated polyethers, fluorinated polyesters, polyetherketones, e.g., PEEK, nylons, or acetal resins. Examples ofself-lubricating polymeric compositions include a resin component andfrom about 30 wt. % to about 0.5 wt. % of a lubricating system. Resincomponents useful in the polymeric composition can be selected frompolyamides, polyesters, polyphenylene sulfides, polyolefins,polyoxymethylenes, styrene polymers, and polycarbonates. The lubricatingsystem of the present invention can be characterized as containing alubricating amount., sufficient to reduce friction and wear, of theresin component and can include polytetrafluorethylene, stearates, andcalcium carbonates. Many other materials, including solid lubricants andfibers, e.g., graphite, mica, silica, talc, boron nitride and molybdenumsulfide, paraffin waxes, petroleum and synthetic lubricating oils, andother polymers, e.g., polyethylene and polytetrafluorethylene, can beadded to the resin component to improve friction properties.

Embodiment No. 12

[0141] This invention provides a safety technique to determine when theposts are consumed. Embodiments include incorporating a tracercomponent, such as an inert chemical, to provide a warning as to thenumber of wafers capable of being polished by the partially consumedweb. In another aspect, a notch or a bar is provided for a mechanicalindication. See FIG. 11.

[0142] Some indicators are higher than the surrounding, to indicate theend of the CMP process. When the indicator or bar is reached, only acertain amount of height remains. This can be detected by visuallyinspecting or by physically sensing the height to determine when theheights of the post and wear bar are equal.

Embodiment No. 13

[0143] This invention resides in providing a mechanical means, such as anotch, to determine when approaching the end of the abrasive web roll.See FIG. 12. When advancing the web, it is advantageous to know when theend is approaching to avoid running out of roll. A notch is providedwhich can be detected either mechanically or optically, similar to thedots that flash to indicate to a projectionist in the movie theater thatthe end of a reel is approaching, or the prink stripe in cash registerreceipts, preferably, on the web back to avoid impacting the process.

Embodiment No. 14

[0144] The invention resides in coding the web throughout its length toenable determining the location of different portions of the web. Barcodes or a number readable with optical character recognition can beused. Little holes can be punched through to provide a detectablepattern. Any type of encoding along the length of the web can beprovided and read with an appropriate type of sensor. The inventiveconcept involves encoding the location along the length of the web.There are at least two benefits. One is real time feedback and any kindof motion control. For example, the length of a moving web is determinedwith feed back control to activate a command signal to advance the web.A second benefit is that the amount of web advanced can be read. Thisenables: (1) good tracking of wafers polished to location on web; and(2) determination of the proximity to the end of the web and alarm foran operator to replace the web.

Embodiment No. 15

[0145] A thin monolayer, e.g., one millimeter, of diamond is formed onthe web posts containing silicon carbide particles, and chemicalpreconditioned to remove about 500 A° of matrix from the top of theposts to expose the diamonds, as by chemical preconditioning using heator solvent to selectively remove the matrix.

[0146] This embodiment advantageously prolongs the wear rate of the webthrough the use of superabrasive, a term used in the industry for a veryhard material, e.g., diamond, or cubic boronitride. The wear rate of theposts are reduced to the extent that they don't change appreciativelyover time, thereby improving CMP uniformity.

Embodiment 16

[0147] This invention resides in providing perforations in the sides orend of the web for improved handling. Rolls can be provided withsprockets to engage the perforations.

[0148] The present invention is applicable to all types of fixedabrasive articles, including rotating polishing pads that aresubstantially circular and substantially rectangular polishing sheets.The present invention provides wafer-to-wafer rate stability for CMP andcan be employed during various phases of semiconductor devicemanufacturing. The present invention, therefore, enjoys utility invarious industrial applications, particularly in CMP in thesemiconductor industry as well as the magnetic recording media industry.

[0149] Only the preferred embodiments of the present invention and but afew examples of its versatility are shown and described in the presentdisclosure. It is to be understood that the present invention is capableof use in various other combinations and environments and is capable ofchanges and modifications within the scope of the inventive concept asexpressed herein.

1. A fixed abrasive article comprising a three-dimensional abrasivecomposite in the form of abrasive composite elements, and furthercomprising a wear indicator.
 2. The fixed abrasive article of claim 1wherein the three-dimensional, fixed abrasive article is textured. 3.The fixed abrasive article of claim 1 comprising erodable abrasivecomposite elements.
 4. The fixed abrasive article of claim 3 wherein theabrasive composite elements comprise a plurality of cylindrical posts.5. The fixed abrasive article of claim 1 comprising a precisely-shapedabrasive composite.
 6. The fixed abrasive article of claim 1 wherein thewear indicator comprises a visible marker in a binder.
 7. The fixedabrasive article of claim 1 wherein the marker comprises a metallicmaterial, a visible material, or a magnetic material.
 8. The fixedabrasive article of claim 1 wherein the wear indicator comprises acolored marker.
 9. The fixed abrasive article of claim 8 wherein thecolored marker is chosen from the group consisting of a dye, a pigment,or a colorant.
 10. The fixed abrasive article of claim 1 wherein thewear indicator comprises a visible marker contained in a binder.
 11. Thefixed abrasive article of claim 1 wherein the wear indicator comprisesan abradable wear indicator coated on an abrasive surface of the fixedabrasive article.
 12. The fixed abrasive article of claim 1 wherein thewear indicator comprises an abradable wear indicator embedded in anabrasive composite.
 13. The fixed abrasive article of claim 1 whereinthe wear indicator comprises a visible marker contained in a lower tenpercent by height of an abrasive composite element.
 14. The fixedabrasive article of claim 1 wherein the wear indicator comprises a wearindicator composite comprising a wear indicator and a binder adhered toa base, wherein upon contacting the substrate the wearindicator-composite element indicates contact between the wear indicatorand the substrate.
 15. The fixed abrasive article of claim 1 wherein thearticle comprises a fixed abrasive pad.
 16. The fixed abrasive articleof claim 1 wherein the article comprises a fixed abrasive belt.
 17. Afixed abrasive article comprising posts having an inert chemical ormechanical indication to indicate post consumption.
 18. The fixedabrasive article of claim 17 wherein the fixed abrasive article is apad.